Preparation

In medium heavy saucepan, combine 4 cups water, rice, and 1 tablespoon salt. Bring to boil, then reduce heat to low and simmer, covered, until rice is tender and water is absorbed, about 20 minutes. Set aside to cool.

In large skillet over moderate heat, heat 1 teaspoon oil until hot but not smoking. Add beef and 1 teaspoon salt. Sauté, stirring occasionally and breaking up large lumps with wooden spoon, until meat is browned, about 10 minutes. Stir in peas, sauce, and garlic powder and simmer, uncovered, until most of liquid is absorbed, about 5 minutes. Transfer to large bowl and set aside to cool.

Line 2 large baking sheets with wax paper. In large bowl, mix together rice, mozzarella, Parmesan, parsley, egg yolks, pepper, and 1 teaspoon salt. Wet hands, scoop up about 2 tablespoons mixture, and roll into 2-inch ball. Poke small hole into center of ball and insert 1 scant tablespoon meat mixture. Re-form into ball and place on baking sheet. Repeat with remaining rice and meat mixtures, placing all balls on 1 baking sheet.